Bleaching tablet



unuoo ncrcmzNUL LXAMINH United States Patent 3,429,821 BLEACHING TABLET Bernard Wein stein, Plainfield, Daniel H. Terry, Cranford, and Harold S. Jensen, Westfield, NJ., assignors to American Home Products Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed June 21, 1966, Ser. No. 559,072 U.S. Cl. 252-97 Claims Illlt. Cl. C09k 3/00;C1ld 9/30 This invention relates generally to bleaching compositions and more particularly to bleaching compositions in tablet form suitable for use in clothes washing machines.

There are bleaching compositions presently obtainable commercially in liquid and powder forms which furnish available chlorine as the bleaching agent. These forms of chlorine-furnishing bleaching compositions have the common disadvantage that the amount thereof to be introduced into a given wash load have to be measured or guessed by the user. Moreover, because of their flowable form, they are apt to be spilled inadvertantly with a potential danger to the user and/or the surroundings. i

In recognition of the aforesaid serious disadvantages of the liquid and powder forms, attempts have been made to provide chlorine-furnishing bleaching compositions in tablet form, which would facilitate handling and introduction of a predetermined amount of bleaching activity per tablet. However, the bleaching compositions in table form so far proposed have lacked one or more of such desirable attributes as, high breaking strength during shipping, storing and/or handling; dependable stability during storage prior to use; and rapid and effective dissolution in water to assure maximum and uniform bleaching action in use.

With the above-noted disadvantages of the known chlotine-furnishing bleaching compositions in liquid, powder, and even in tablet form, in view; it is a primary object of this invention to provide a chlorine-furnishing bleaching tablet which does exhibit all of the desirable characteristics of high breaking strength, dependable stability, and rapid and effective dissolution in water.

A further object of this invention is to provide a bleaching tablet of .the foregoing characteristics which also furnishes a uniform and high degree of bleaching action per unit.

Other objects and advantages of the invention will appear from the description thereof that follows:

Generally, the foregoing objects are attained, in accordance with the present invention, by the provision of a other alkali metal salts included in the formations of the invention.

The alkali metal phosphate is preferably present in the form of sodium tripolyphosphate, and functions as a buffer 5 and water softener, as well as a detergent builder. The

sodium tripolyphosphate may be replaced in certain instances with potassium tet'rapyrophosphate or sodium trimetaphosphate, for example.

The anionic surfactant, if included, may be selected from the class of synthetic detergents broadly described as the water-soluble salts of organic sulfuric reaction products having, in the molecular structures thereof, an alkyl group containing from about 8 to about 22 carbon atoms and a radical selected from the group consisting of sulfonic acid and sulfuric acid ester radicals. Examples of the synthetic detergents which form part of the preferred compositions of the present invention are the sodium or potassium alkyl benzene sulfonates in which the alkyl group contains from about 9 to about carbon atoms;

e.g., sodium dodecyl bengene sulfonate, and those sulfonates of the types described in U.S. Patent 2,220,099 and U.S. Patent 2,477,383. As is well known in the art, other anionic surfactants, such as sodium lauryl alcohol sulfonate and the sodium alkyl glyceryl ether sulfonates, and

others of similar function, a number of which surfactants tablets obtained are substantially worthless in that they have low breaking strength, which renders handling and packaging thereof impractical. On the other hand, if the proportion of sodium stearate is increased, say to 4 percent of total composition; the resulting tablets are extremely hard and virtually insoluble.

Similarly, the salt, selected from the group consisting of sodium chloride and spdium sulfate, which performs the function of providing th'e tablets of the present invention with optimum dissolution characteristics, may not be substituted. Thus, sodium carbonate, which has been used for such purpose in other formulations, is completely unsuitable for such purposes in the present formulations, as will appear from the more detailed description hereinafter. Moreover, of the two salts usable in the tablets of bleaching tablet whicrcompris vs com-poundwelectech' the'invention, sodium chloride is preferred.

from the group consisting of dichlorocyanuric acid, and the alkali metal salts thereof; an alkali metal phosphate of the group consisting of alkali metal tripolyphosphates, alkali metal tetrapyrophosphates, and alkali metal trimetaphosphates; a salt selected from the group consisting of sodium chloride and sodium sulfate; and a soap composition that comprises both sodium coconut soap and sodium tallow soap. An anionic or non-ionic surfactant may be added to the tableting composition, but is not essential thereto.

The dichlorocyanuric acid, or alkali metal salt thereof, functions as a source of bleaching chlorine, which is provided when the tablet is dissolved in water. Although the potassium salt of dichlorocyanuric acid and the acid per se have been found useful in the tablets of the invention, the sodium salt is preferred. Furthermore, both said sodium and potassium salts of dichlorocyanuric acid are preferable to the other alkali metal salts thereof, since the former are more readily dissolved in water, and are easily removable from clothes by rinsing. In certain instances, as already indicated, the acid itself may be used, although the latter has the drawback of tending to react with the In the formulations in accordance with the present invention, the alkali metal salt of dichlorocyanuric acid, or the acid per se, may comprise from about 15 to about 55 50 parts by weight of the total compositions. In the event less than the minimum proportion stated is employed, the resulting tablets provide insuflicient bleaching action per unit. On the other hand, increasing the proportion of the alkali metal salt of dichlorocyanuric acid, or the acid per se, in the compositions, appreciably beyond that referred to, results in lack of economy and, moreover, prevents the employment of sufficient amounts of the remaining ingredients to obtain tablets of the optimum characteristics afforded by the invention. Preferably, from about to about parts by weight of the alkali metal salt of the dichlorocyanuric acid are included in the formulations.

The alkali metal phosphate may be present in the formulation in the proportion of from about 20 to about 7 parts by weight of total compositions and preferably from detergent buildup. Upon inclusion of greater proportions than the maximum stated, the proportions of the other components required in comparatively large concentrations; i.e., the alkali metal salt of dichlorocyanuric acid (or acid per se) and the sodium chloride (or sulfate) are reduced to the extent that the desired characteristics, with 5 the tablets.

TABLE A.PERCENT BY WEIGHT Example Component I II III IV V VI VII Sodium salt of dichlorocyanuric acid- 40. 00 a0. 00 20130 40. 0O 40. 00 20.00 40. 00 Sodium trl lyphosphate 30. 00 40. 00 50. 00 30. 00 30.00 15. 00 30. 00 Sodium ch orlde 25. 80 26.00 26.00 26. 80 25.80 61. 80 25.80 Sodium dodecyl benzene sulionate in form 2.00 2.00 2.00 1.00

Lauryl alcohol sulfate 2. 00 Ivorybeads! 2.00 Ultramarine blue. 0. 20

l A mixture of sodium coconut and tsilow soaps.

respect to bleaching activity and quick solubility are adversely affected.

The anionic surfactant may be present in amounts from about 0.05 to about 3 parts by weight, as is known in the detergent art. Lesser amounts give insufficient detergent action, while greater amounts may result in undue sudsing.

The sodium chloride or sulfate may be present in the formulations in proportions that range from about 20 to about 30 parts by weight of the compositions. Lesser proportions do not give significant advantages in dissolution characteristics, whereas greater proportions function as substantially inert filler which diminishes both the proportion and activities of the alkali metal salt of dichlorocyanuric acid (or acid) and the alkali metal phosphate.

In accordance with an important feature of the invention, the soap component comprises 85-90 percent sodium tallow soap and -15 percent sodium coconut soap.

The soap component containing the specified ingredients is present in the final tablet in proportions of from about 1 to about 3 parts by weight thereof. Lesser proportions of the soap component result in tablets of completely inferior breaking strength, whereas greater amounts adversely affect the solubility characteristics and may also provide undue sudsing. Preferably, the soap component is utilized in bead form in preparing the tablets, as referred to hereinafter.

In preparing bleaching tablets in accordance with the present invention, the components may be thoroughly admixed by simple and known mixing operations. Thereafter, the composition may be tableted by again conventional procedures, but preferably so that the compaction ratios of the ingredients after the mixing as compared to the finished product, is about 1 /521. The diameter of the tablets may vary from aspirin size up to about 3 inches in diameter. The number of tablets used for giving adequate bleaching is obviously dependent upon the total available chlorine in parts per million, and this in turn limits the number of tablets needed to give adequate bleaching.

As illustrative of formulations which provide tablets having the desired characteristics with respect to quick dissolution in water and high breaking strength, as well as optimum bleaching characteristics, there are given below the following examples.

Examples I-VII Separate batches of 100 pounds each of bleaching compositions were prepared from ingredients which were mixed in the proportions given in the respective formulations set forth in Table A below. In each instance, the ingredients were mixed thoroughly in conventional mixing apparatus; i.e., a Muller mortar mixer, to insure that uniform mixtures were provided for tableting. Thereafter, the mixtures were tableted by means of conventional tableting apparatus; i.e., a Stokes Model R single station, single motion ceramic compacting press, into diameter The tablets obtained by compaction of the foregoing formulations in the manner referred to hereinbefore, surprisingly showed, regardless of the tableting size, a crushstrength of from 40-50 pounds. Moreover, the tablets were non-tacky and stable on storage, but disintegrated in approximately 30 seconds in water having temperatures of 140 F. and above. Tablets of 1% inches diameter of a thickness to provide 50-52 grams of composition were produced which would be approximately the unit size and weight practically useful for consumer applications.

With respect to the last, an identifying color dye may be employed as in several of the formulations of the examples. As will appear to those skilled in the art, other commercially obtainable dyes may be substituted; e.g., and C. Blue No. 2. The criterion for selection, apart from mere choice of color, would reside in choosing a dye stable to chlorine. Such a dye, if employed, may be incorporated in the formulations of the invention in varying concentrations, preferably in the range of .05 percent to .3 percent by weight of total composition.

Bleaching tablets, prepared in accordance with the invention, to weigh from 25-27% grams, as well as the 50 52 grams size referred to above; additionally have bleaching properties superior to many existing chlorine compounds. Thus, the smaller size tablets deliver -110 p.p.m chlorine, whereas the larger size tablets deliver 200- 210 p.p.m. cholrine. In both cases, the tablets have been found to give bleaching performances proportional to the available chlorine.

Example VIII Following the procedures of Examples I-VII, and utilizing the formulation of Example I, a number of bleaching tablets, each of 1% inches in diameter, but of varying thicknesses, as referred to hereinafter, were prepared. These tablets were tested for crush strength and for disintegrating time in agitated water at a temperature of F. The different thicknesses of the tablets tested, the number of tablets tested at each such thickness, the average crush strength in pounds for each tablet thickness and weight, the weight in grams of each tablet at a given thickness, and the average disintegration time in seconds under the said conditions, are given as averages in Table B below:

Again following the procedures of Examples I-VII, but in this instance utilizing the two separate formulations given in Table C below, a number of bleaching tablets, again of 1% inches in diameter, but of uniform thickness 5 as well as weight, were prepared and similarly tested for crush strength and disintegrating time. The thickness, weight of the number of tablets used, and the results of the test, are all given as averages in said Table C below:

6 tetrapyrophosphates and alkali metal trimetaphosphates; from about 20 to about 30 partsfby weight of a salt se lected from the group consisting of sodium chloride and sodium sulfate; and from about 1 to about 3 parts by weight of a soap composition consisting essentially of TABLE 5 A B from about to about parts by weight of a sodium coconut soap, from about 85 to about 90 parts by weight Formulations (parts by weight): of a sodium tallow soap.

283% a igg f gmi'ffiifi 3 gg 2. A crush-resistant, easily soluble, bleaching tablet as g g me- 2&8 10 defined in claim 1, which also contains from about 0.05 to 8 2 2 about 3 parts by weight of a surfactant selected from the 3 "i'"' g p CODSISUDE f n nlc and non-101116 Synthetic dc ggp M "5"? h t t 1 b1 b] a: crus -res1s an east y so u e, eac mg ta et as $3 3,,32fii13552; 3 3 15 defined in claim 1, which consists essentially of from about 5:31? t l i c i gsagm h g 3 35 to about 45 parts by weight of said compound of the ZQ Ffi j: 36 56 group consisting of dichlorocyanuric acid and the alkali metal salts thereof; from about to about parts by As appears from the foregoing, bleaching tablets preweight of said alkali metal phosphate; and from about pared in accordance with the invention (Formulation A 20 20 to about 30 parts by weight of said salt. above), show more than 70 percent improvement in crush 4. A crush-resistant, easily soluble, bleaching tablet as strength and more than percent improvement in disintedefined in claim 3, which also comprises from about 0.05 gration time, over bleaching tablets prepared from a very to about 3 parts by weight of a synthetic anionic surclosely similar formulation (Formulation B above), which factant. differs only in use of a comparable amount of a conven- 25 5. A crush-resistant, easily soluble, bleaching tablet as tional soap as binder material for tableting. defined in claim 4, which consists essentially of about 40 parts by weight of the sodium salt of dichlorocyanuric Examples X XIV acid; about 30 parts by weight of sodium tripolyphos- Using the procedure of Example I, bleaching tablets of phate; about 2 parts by weight of sodium dodecyl ben- 1% inches in diameter, and of a final thickness to pro- 30 zene sulfonate; about 25 parts by weight of sodium chlovide -52 grams of composition, are prepared from the ride; and about 2 parts by weight of said soap com formulations given in Table D below: position.

TABLE D.PERCENT BY WEIGHT Example Component X XI x11 x111 xtv Sodium salt 0! dlchlpocyanuric acid.

Sodium sulfate Sodium dodecyl benzene sullonate beads 2. 00 2. 00 2. 00 2. 00 2. 00 0. 20 0. 20 0. 20

sistiug of alkali metal tripolyphosphates, alkali metal an alkali nretar'pirosphatrwlected from thegroupcon References Cited UNITED STATES PATENTS 3,154,494 10/1964 Speak 252-96 MAYER WEINBLATT, Primary Examiner.

' US. Cl. X.R. 25298, 99 

1. A CRUSH-RESISTANT, EASILY SOLUBLE, BLEACHING TABLET, CONSISTING ESSENTIALLY OF: FROM ABOUT 15 TO ABOUT 50 PARTS BY WEIGHT OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF DICHLOROCYANURIC ACID AND THE ALKALI METAL SALTS THEREOF; FROM ABOUT 20 TO ABOUT 50 PARTS BY WEIGHT OF AN ALKALI METAL PHOSPHATE SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL TRIPOLYPHOSPHATES, ALKALI METAL TETRAPYROPHOSPHATES AND ALKALI METAL TRIMETAPHOSPHATES; FROM ABOUT 20 TO ABOUT 30 PARTS BY WEIGHT OF A SALT SELECTED FROM THE GROUP CONSISTING OF SODIUM CHLORIDE AND SODIUM SULFATE; AND FROM ABOUT 1 TO 3 PARTS BY WEIGHT OF A SOAP COMPOSITION CONSISTING ESSENTIALLY OF FROM ABOUT 10 TO ABOUT 15 PARTS BY WEIGHT OF A SODIUM COCONUT SOAP, FROM ABOUT 85 TO ABOUT 90 PARTS BY WEIGHT OF A SODIUM TALLOW SOAP. 